Thermostatic-control electrical heater plug



Aug. 30,1927; 1, 41,002

L. M. KAPLAN THERMOSTATIC CONTROL ELECTRICAL HEATER PLUG Filed Oct. 27, 1926 Patented Aug. 30,1927.

LOUIS M. KAPLAN, OF PHILADELPHIA, PENNSYLVANIA.

rnnnnosmrrc-comnon nrnc'rarou. nna'rnn .PLUG.

Application filed October a7, 1920. Serial 110'. 144,445.

. My invention relates to a new and useful improvement in a temperature control elec-' t-ric attachment plug, for electrical heat ng appliances such as lIOIlS, toasters, percplators and the like, and it relates more particularly to a novel construction therein, whereby an easy and quick adjustment of the temperature of the heating appliance may be obtained.

My invention relates more particularly to an electrical attachment or connection plug, adapted for electrical heating appliances such as electrical irons, toasters, percolators, wafile irons and the like, which is provided 1 with a built-in thermostatic control switch. which will automatically break the electrical circuit to the heating appliance, when the temperature of the latter rises above'a predetermined point and wherein said switch will automatically close when the-temperature of the heating appliance falls below the predetermined point-.-

. My invention relates further to a thermostatic control electrical'heater" plug of the character stated, in which the temperature limit may be adjustedor varied at will, be-

tween suitable limits, by the mere-manual 1 turning of an adjustment knob or handle on the exterior of the plug, which may be eas- 3 ily manipulated by anyone. a

For the purpose of illustrating my invention, I have shown .in the accompanying drawings, forms thereof which are at present preferre d'iby me, since they will give 86 in practice, satisfactory and reliable results, although ,it is to be understood that the various instrumentalities offwhich my inven tion consists can be variously arranged and organized and that my invention is not li1n ited to the precise arrangement and organization of these 'instrumentalities as herein shown and described.

In the accompanying drawlngs.

, Figure 1 represents a perspective view of:-

a thermostatic control electrical heater plug embodying my invention.

Figure 2 represents a plan View of the'deviceshown in Fig. 1,,the upper half of the housing being removed- I Figure. 3 represents a section on line. 3-3

of Figure-2.

Figure 4 represents. asection on line 4-4 of Figure 2,

/' Referring to thedrawings, in which like reference charactersindicate like parts, 1'

designates the outer longitudinally divided ing) we two part insulatin housing of the electrical heater plug 0 my novel construction, a

comprising the two similar halves 2 and 3, having the' contiguous inner surfaces .4,

abuttin ,each other. The upper or rear end of the ousing is provided with an axial opening 5 for the reception-0f the helical spring coil cord support 6, and for the passage 1nto the housingof the electrical cord orwire7. i

A plair of substantially parallel'longitudi nal c ambers or recesses8 and 9 are pro-- vided in the housing 1, equally divided between the upper and lower halves 2 and 3 thereof, and opening at the lower end 10 of the housing, while terminating within the housing, near the 'upper end thereof. Inv v the recesses or contact chambers 8 and 9, 5 corresponding contact members 11and 12 respectively are positionedfadapted to engage the contact pins of an electrical heating applialnce, and to make electrical contact therewit v v Each of the contact members '11 and 12 is 7 generally U shaped, as shown particularly prongs 13 of the electrical contact members 11 and 12, the contact is made substantially at the center or bowed'portion 18 of said limbs 13, and the contact is maintained by the resiliency of the limbs 13, said limbs or prongs 13 being slightl bowed at the central portions 1 8 thereofz and the prongs 13 being supported by the housing, at thetwo oints 16 and 17 as mentioned hereinbefore; y this novel construction of the contactsaid limbs.*

members the strain is relieved at the 19 connecting the two limbs 13, and isborne entirely by the bowed portions 18 ofmember 11 and 12, is provided with a transyersely extending anchor member 20, formed integrally therewith, and adapted to interlockwith aledge or shoulder 21 formed in the body of the housing, thereby to prevent the longitudinal movement of said contact members 11 and 12. A longitudinal 'exten-, v

sion 22 is also formed integrally with each of the connecting webs 19, of the contact members 11 and 12, extending longitudinally of said contact members and rearwardly thereof, to which suitable contact plates 23 and 24 are secured, by a bolt, rivet, or other fastening means 25 and 31 respectively, as shown particularly in 'Figure 2. Each of the contact plates or strips 23 and 24:, extends rearwardly substantially parallel to each other and the free terminals thereof are enclosed in suitable recesses 26, thereby to anchor the contact members 11 and 12, against any rearward longitudinal movement thereof.

Each of the contact strips or plates 23 and 2 1 is provided with an aperture 27, therein, through which one of the two wires of the electrical cord 7 is adapted to pass, and is also provided with a binding screw .28, threaded into said contact plates 23 and 24, adapted tosecure the terminals of the lead wires.

A thermostatic element 29, comprising a coupling of two dissimilar metals, such as iron and brass, and of generally U shape, is provided, with a shorter limb thereof interposed between the contact strip 24: and the longitudinal member 22 of the contact member 12, as shown particularly in Figure 2. The shorter limb 30 of the thermostatic element 29 is thus in direct contact with the member 22 of the contact member 12 and is also secured by the common bolt or screw 31, while an electrical insulating bushing 32 and insulating washers 33 are provided, intermediate the screw 31 and the contact plate 24: and the limb 30 of the thermostatic element 29 and said contact member 24 respectively, electrically to insulate the contact plate 2 1 from both the thermostatic ele ment 29 and from the contact element 12.

The contact plate 21 carries a boss or lug 34, through which a threaded opening 35 provided, which is adapted to receive an adjustment screw 36. The inner end of the adjustment screw carries a contact point 37 of a suitable heat resisting metal or alloy such as tungsten, silver, platinum or the like, and a corresponding contact point 38 is carried by the thermostatic element 29, in operative alignment with the contact point 37. To the outer end of the adjustment screw 36, an operating handle or knob 39 is secured, which projects through an opening 40 in the side walls of the two housing members 2 and 3, and extends to the exterior,

as shown particularly in Figure 2. The knob 39 also carries a pointer or finger 41, while the housing carries a fixed stop 42. By this means the rotary movement of the adjustment screw 36 is limited.

According to vmy novel construction, the thermostatic element 29 is composed of any two metals having different coefficients of in mechanical and electrical contact with the contact point 37 carried by the set screw 36.

In use, the plug 1 is applied to the terminal pins or contact points of the electrical heating appliance. As the temperature of the heating appliance rises above a predetermined point, the contact elements 11 and 12, being in direct mechanical contact with the contact pins olf the electrical appliance, also rise in temperature and the heat is transmitted through the element 22, to the thermostatic element 29. The thermostatic element 29, due to the rise in temperature, buckles or is deflected outwardly in the direction indicated by the arrow 43. This deflection oi the thermostatic element 29 separates the two contact points 37 and 38, thereby breaking the electrical connection and hence the electrical circuit, through the heating appliance. As the temperature of the heating appliance drops again, and the temperature or the contact member 12 and of the thermostatic element 29 also drops, said thermostatic element 29 is deflected in the opposite direction and thus again establishes contact between the two points 37 and 38, thereby reestabli--1hing the electrical circuit through the electrical heating appliance. This action is entirely automatic both in opening and closing the circuit.

In order to adjust the plug 1 to any desired temperature, within the limits of the device, it is merely necessary to turn the knob 39. Thus, if it is desired to set the device for a relatively low temperature, that is, so to set the same that the electric circuit will be broken when a certain predetermined, relatively low temperature has been reached, it is merely necessary to turn the knob 39 in a counterclockwise direction thereby lessening the pressure of the adjustment screw 36 against the contact point 38 of the thermostatic element 29. In this position, a relatively small amount of heat or degree of temperature will be enough to deflect said thermostatic element away from the contact point 37 on said adjustment screw 36 sufliciently tobreak the circuit. On the other hand if it is desired to set the device for a relatively high temperature, the knob 39 is turned in a clockwise direction thereby pressing the adjustment screw 36 inwardly against the contact point 38 of the thermostatic element 29 in which position a greater degree of heat or temperature is required to deflect said thermostatic element 29 sufficiently to separate the contact points 37 and 38 to break the circuit.

In Figures land 2 the knob is shown in the position of the highest temperature adjustment.

llll) The two halves 2and 3 of the housing are secured to each other by any suitable means such as the screws 44 and corresponding nuts.

It will now be apparent that I have devised a novel'and useful thermostatic control electrical heater plug, which embodies the features of advantage enumerated as desirable in the statement of the invention and the above description, and while I have, in the present instance, shown and described preferred embodiments thereof which will give in practice, satisfactory and reliable results, it is to be understood that such embodiments are susceptible of modification in various particulars without departing from the scope or spirit ,of the invention or sacrificing any of its advantages.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1. In a device of the character stated, a] longitudinally divided two part housing of insulating material, having a pair of parallel longitudinal rec sses therein, open at one end of said housing, pin receivingspring contact members disposed Within said'recesses each comprising a pair of resilient coacting spring prongs, a terminal contact plate, secured toone of said spring contact members in electrical contact therewith, a

thermd-sensitive element secured .to the other of said spring contact members and in electrical and mechanical contact therewith, a second terminal contact plate secured to said last spring contact member and electrically insulated therefrom and from said thermosensitive element, an adjustment screw extending through the wall of said insulating housing and through said second terminal contact plate, threadedly engagingthe latter, a contact point carried by the inner end thereof, a second contact point carried by the thermo-sensitive element in operative alignment with and normally in contact with said first contact point, said thermo-sensitive element being adapted to deflect upon a predetermined rise in temperature, thereby breaking the contact between saidtwo contact points, said adjustment screw being adapted to be turned manually from without the plug,

thereby to vary the temperature at which said contact points are separated.

'2. In a device of the character stated, a longitudinally divided'two part housing of insulating material, having a pair of parallel longitudinal recesses therein, open at one wall of said insulating housing and t irough said second terminal contact plate, thread- .edly engaging the latter, a knob carried by the outer end ofsaid adjustment screw, a contact point carried by the'inner end thereof, a second contact point carried by the thermo-sensitive element in operative alignment with and normally in contact with said first contact point, said thermo-sensitive elementbeing adapted to deflect upon a predetermined rise in temperature,'thereby breaking the contact between said two contact points, and said adjustment screw being adapted to be turned manually from without the plug, thereby to vary the temperature at which said contact points'are separated.

LOUIS M. KAPLAN. 

